CPUs are designed for a certain Bus speed (FSB) and they will multiply that speed to achieve their rated speed in MHz.
So, motherboards don't really have a maximum CPU speed.
They may quote the maximum chip they can run at that particular point in time, but who knows what tomorrow will bring...
Lets say your FSB is 133MHz, so your 1.2GHz would run 133 x 9. If you put in a CPU with a multiplier of 12 (the multipliers are mostly locked now, to allow the mfg to warranty them) then you get 1.6GHz, and the motherboard will not even 'know' the difference.
BIOS updates include microcode updates that will ID the latest CPUs when your computer POSTs.
The motherboard also needs to ID the CPU in order to supply it with the correct voltage, and to advise the OS what the CPU is capable of (MMX, SSE, 3dNow! etc.)
But, if apples-are-apples and you get a new chip with only a higher multiplier, you could be just fine
Don't fry up any CPUs with bad voltage, though...
(important safety-tip) LoL
Regards

Well, it is the Binary Input/Output System for your motherboard, and I have described some of its function above. Also herehttp://forums.afterdawn.com/thread_view.cfm/1/105406#558142
is a fellow with some BIOS 'challenges'...
In the 'old days' prior to 1995, we would build a PC and once it displayed a command prompt [bold]c:\[/bold] it was done "Ship it out"
But today, your fun is only just beginning...
Anyway, the BIOS is 'everything' - don't even take your Windows CD out of the case until your BIOS is all set up properly! The BIOS is responsible for all hardware stability.
People should still boot a newly-assembled PC into DOS and take a look at things like IRQ assignments (PCI expansion slots that share IRQs - avoid if possible) before handing things over to the plug & play operating system.
So the BIOS runs the hardware. An update will allow newer hardware (ie. HD over 65GB) and will fix 'issues' that have been discovered by people trying to operate their PCs.
The 'final' BIOS revision is the one you want.
Usually all the bugs are thoroughly ironed-out and the BIOS has been tuned for maximum performance...
A classic example is Asus.
If the MSI or ABit mobo is faster in benchmarking (you know, like on Tom's Hardware) Asus will come right back with a new BIOS revision, to address that little problem and make things right
L8R